Spark plug



June 6, 1933. w DAVls 1,912,516

SPARK PLUG Filed July 30, 1931 gwuento'o W5. Dave's,

atenterl June ti, 1933 STATES WILLIAM E. DAVIS, 01? EVART, MICHIGAN SPARK PLUG App1ication filed July 30, 1931.

The invention appertains to an electric igniter, such as a spark plug for internal combustion engines, and provides an article which presents a plurality of spark gaps and 5 precludes ready fouling by accumulation of oil or soot, hence assuring positive firing of the engine when the latter is running.

The invention provides a secondary or ground electrode of peculiar structure embodying a stem and spaced lateral branches, the lower branch terminating in line with the primary or central electrode, and the upper branch being notched in its end to receive the primary electrode and form in effect an approximately semi-circular spark gap.

The branches curve outwardly and downwardly to prevent oil from accumulating and obstructing the spark gaps.

90 Other ob ects and advantages will be apparent as the nature of the lnvention is d1sclosed, and to this end reference is to be had to the following description and to the drawing hereto attached, in which Figure 1 is a perspective view of a spark plug embodying the invention.

Fig. 2 is an end view of the plug.

Fig. 3 is a fragmentary view, partly in section.

Corresponding and like parts are referred to in the following description and indicated in the several views of the drawing by like reference characters.

The numeral 1 designates the usual body or metallic shell of a spark plug, in which is fitted a core 2 of porcelain or other nonconducting material. The primary or central electrode is designated by the numeral 3, it extends longitudinally and coacts with a secondary or grounded electrode which is carried by the shell or body 1.

The secondary or grounded electrode comprises a vertical or longitudinal stem 4 and lateral branches to wit, an upper branch 5 and a lower branch 6 which, as shown most clearly in Fig. 3 of the drawing, curve respectively outwardly and downwardly to prevent oil accumulating in the spark gaps and fouling the plug. The lower branch 6 terminates in line with the primary or central electrode 3 and is spaced therefrom a distance Serial No. 554,085.

to provide a spark gap. The upper branch 5 1s notched in its end to provide a spark gap 7 of approximately semi-circular outline, with the result that a number of sparking points are provided. The terminal portion of the electrode 3 is received in the notch forming the semi-circular spark gap 7. The parts are so disposed .as to admit of the ready separation of the plug for replacement or any other desired purpose, as well as to facilitate the assemblage of the parts when placing them in position. The secondary electrode may be attached to the shell or body 1 in any determinate way, and this is effected by introducing the stem 4 into an opening formed in the lower end of the part 1, as indicated most clearly in Fig. 3 of the drawing.

It will be understood from the foregoing, taken in connection with the accompanying drawing, that the invention results in the 7 provision of a spark plug which is not liable to be readily fouled by an accumulation of oil or soot, and which therefore assures positive sparking and a smooth running engine.

It is observed that a terminal spark gap is provided between the extremity of the electrode 3 and the branch 6, and that a continuous spark gap is provided between the end portion of the electrode 3 and the branch 5, hence points are provided for the positive passage of the spark when the device is in ac tive service.

What is claimed is 1. A spark plug embodying the usual metal shell and central electrode insulated therefrom, a secondary electrode carried by the shell and comprising upper and lower branches, the latter terminating in line with and below the central electrode and spaced therefrom, whereas the upper branch is notched in its end to receive the end of the center electrode and form a continuous spark gap therewith.

2. In a spark plug embodying a metal shell and the usual center electrode insulated therefrom, a secondary electrode carried by the shell and comprising upper and lower lateral branches which curve respectively outwardly and downwardly, the lower branch terminating opposite but below the extremity of the '100 center electrode and the upper branch being notched in its end to receive the end portion of the center electrode and form an approximate spark gap therewith of semi-circular outline.

3. A spark plug comprising the usual metallic body and center electrode insulated therefrom and a secondary electrode comprising a stem attached to the body and upper and lower lateral branches which curve respectively outwardly and downwardly, the lower branch terminating in line with but below the center electrode and spaced therefrom to provide a terminal spark gap, and the upper branch being notched in its end to receive the end portion of the center electrode and form a lateral spark gap of approximately semi-circular outline.

4. In a spark plug embodying a metal shell and a centrally disposed electrode insulated therefrom, a longitudinal secondary electrode embodying a stem secured in an opening of the shell and upper andlower lateral branches which curve respectively outwardly and downwardly, the lower branch terminating below and in line with the center electrode and being spaced therefrom to form a terminal spark gap, and the upper branch having a notch in its end to receive the end portion of the center electrode and form therewith a lateral spark gap of approximately semi-circular outline thus providing a set of associated spark gaps which function to simultaneously produce a set of longitudinal sparks and a set of transverse sparks.

5. As an article of manufacture, a spark plug electrode having a vertical stem from the lower portion of which there extends laterally a notched upper branch and a lower branch that terminates below the notch of the upper branch.

In testimony whereof I have hereunto set my hand this 28 day of July, 1931.

WILLIAM E. DAVIS. 

